The International Journal Of Engineering And Science (IJES) ||Volume|| 3 ||Issue|| 01 || Pages || 23-29 || 2014 || ISSN (e): 2319 – 1813 ISSN (p): 2319 – 1805
Geophysical Investigation of Weathered Basement, Using Electrical Resistivity Method in Zainawa Village, Kano State, Nigeria 1, 1,
Aliyu N.S, 2, Aminu A.L, and Chiemeke Collins
Department of physics Federal College of Education, Okene, Nigeria. 2, Department of physics Ahmadu Bello University, Zaria, Nigeria.
--------------------------------------------------------ABSTRACT-------------------------------------------------The type of method adopted for this research was the 1D electrical resistivity, using the GEOPULSE Tarrameter. A schlumberger configuration was carried out to map out the Geological features of the earth subsurface. Five profiles were carried out in the study area. Each profile, the layout geometry for the electrical resistivity were the normal schlumberger arrays. The maximum current electrode separation (AB) was 200m, that is, AB/2=100m. The data obtained using Geopulse resistivity Meter SAS 300 were processed using computer software (IPI2Win). Based on the electrical resistivity value obtained in the study area, the following deductions were made. The average depth to the fresh basement is generally beyond 30m. The target area revealed the presence of two distinct layers, the top soil and weathered basement with resistivity range of 20-782Ωm and 100-978Ωm respectively. These layers constitute the overburden with a thickness of 2.1m. The weathered basement underlies the topsoil with an average thickness of 18m and this is a good aquifer in the target area. The depth of probing which is 30m above the fresh basement.
KEY WORDS: Vertical electrical sounding, Zainawa, Geoelectrical section, Resistivity, Aquifer, Alluvial. ------------------------------------------------------------------------------------------------------------------------- -------------Date of Submission: 17 June 2013 Date of Acceptance: 10 January 2014 -------------------------------------------------------------------------------------------------------------- -------------------------
I.
INTRODUCTION
The purpose of electrical surveys, is to determine the subsurface resistivity distribution by making measurements on the ground surface. From these measurements, the true resistivity of the subsurface can be estimated. Exploration for ground water involves the use of various methods applied in the location of water bearing rocks called aquifers. Among the most common aquifers are consolidated sands and gravel of alluvial, glacial, sedimentary rocks especially limestone, dolomite, sandstones, porous or fractured volcanic. Pressure on natural resources from growing populations, with increase demand for water supply for domestic use, infrastructure and housing has increased geometrically over the past decades and can be expected to rise continually. Further, stress on the environment due to population surge and pollution will increase the need for detailed geological knowledge, for geotechnical, hydrogeological and environmental protection purposes. Geophysical methods can play an important role in the acquisition of such knowledge. However, the complete survey procedure, including the data acquisition, data processing, interpretation and presentation must be efficient in terms of time, cost and manpower. Huge amount of money is being spent yearly in Nigeria both federal government and state government for sinking boreholes in other to reduce the perennial scarcity of water to the bearest minimum yet no meaningful result, erosion control and host of others, yet this amount do not justify the work as soon after, the boreholes fails and pollution of ground water continues and erosion is now moving at an alarming speed toward the northern part of the country. This can be effectively managed and controlled if only there is a proper geophysical mapping of the target area. Different lithologic material constitutes majorly the basement complex and sedimentary aquifers. The basement aquifers in the study area are fractured rocks and the weathered in-situ material while the sedimentary aquifers consist of sands and sandstones.
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